A packet relay apparatus that divides received packet data (hereinafter simply called the “packet”) into a plurality of segment data and that switches the respective segment data using a plurality of switches according to the destination of the original packet is proposed.
FIG. 1 is a diagram schematically illustrating the configuration of a packet relay apparatus equipped with a plurality of switches. Reference numeral 200 is the packet relay apparatus, 210-1 to 210-n and 230-1 to 230-n are interface (IF) cards, and 220 is a switch card. Reference numerals 211-1 to 211-n are receiving units, 212-1 to 212-n are data segmenting units, and 221-1 to 221-m are the switches. Reference numerals 231-1 to 231-n are packet assembling units, and 232-1 to 232-n are transmitting units.
The packet relay apparatus 200 thus includes the n interface cards 210-1 to 210-n, the n interface cards 230-1 to 230-n, and the switch card 220. In the interface cards 210-1 to 210-n, the receiving units 211-1 to 211-n each receive a packet, and the data segmenting units 212-1 to 212-n each divide the packet into a plurality of segment data. Each of the data segmenting units 212-1 to 212-n distributes the segment data to the m switches 221-1 to 221-m mounted on the switch card 220.
Each of the switches 221-1 to 221-m transfers each incoming segment data to a corresponding one of the interface cards 230-1 to 230-n that is determined according to the destination of the original packet.
In the interface cards 230-1 to 230-n that received the segment data, the packet assembling units 231-1 to 231-n assemble the segment data into packets. The transmitting units 232-1 to 232-n transmit the packets.
A data receiving apparatus which includes: packet disassembling means for recovering transmission time information and voice or video encoded data by disassembling a packet received over a network; storage means for storing the transmission time information and encoded data recovered by the packet disassembling means; reference time generating means for generating a reference time signal which serves as a reference for determining a timing for reading out the encoded data stored in the storage means and a timing for calculating a relative delay fluctuation time that the received packet experienced during transmission over the network; read timing control means for controlling the read timing to read the encoded data from the storage means, based on the transmission time information stored in the storage means and the reference time signal generated by the reference time generating means; fluctuation time calculating means for calculating, based on the transmission time information recovered by the packet disassembling means and on the reference time signal, the relative delay fluctuation time that the received packet experienced during transmission over the network; smoothing means for smoothing the relative delay fluctuation times that the fluctuation time calculating means calculated for a plurality of received packets; timing adjusting means for monitoring the output of the smoothing means and, in accordance with the output, adjusting the reference time signal generated by the reference time generating means; and decoding means for decoding, in accordance with the reference time signal, the encoded data that has been read out of the storage means by the read timing supplied from the read timing control means is also proposed.
Further, a fluctuation absorbing apparatus which includes: a first queue which stores high priority packets; a second queue which stores packets other than the high priority packets; a classifier which determines whether an incoming packet is a high priority packet or not and which directs the incoming packet to a corresponding one of the first and second queues; a scheduler which externally outputs the packets stored in the first queue and the packets stored in the second queue so that the packets stored in the first queue are output in preference to the packets stored in the second queue; and a packet interval adjusting unit which adjusts the time interval at which the packets are output from the first queue is proposed.
Related art is disclosed in Japanese Laid-open Patent Publication No. 2008-160570, Japanese Laid-open Patent Publication No. 2004-104701 and Japanese Laid-open Patent Publication No. 2005-318075.